In the gas utility industry, it is often required that provision be made to detect attempts to tamper with gas meters, said attempts being either for the purpose of removing the meter to remove a gas blocking plate or to enable the use of gas directly from the supply pipe. For this purpose it has been common to enclose the nut which couples the meter pipe to the supply pipe with a seal in the form of two halves being either fastened together with a lead and wire seal, or being provided with integral means for snapping together in non-revovable engagement.
However the use of such devices has been limited by their expense, and by the fact that it is often possible to remove such seals and replace them without evidence of tampering.